Chamber temperature too high error (H2S)

Bambu Lab H2 Series
1

New to the Bambu world. Can someone help me understand what’s going on here, if only so I can understand the inner workings of this beast. I printed some ASA-CF with the chamber heater off. From what I understand, ASA-CF doesn’t exactly need a chamber heater to print and the profile I imported into Bambu Studio from Polymaker had the chamber heater set to 0C, so I left it like that. Far as I’m aware, 0C also means chamber heater off, so then why do I get errors when the inside of the printer surpasses 43deg and then pauses the print? Why does it start blasting fans to try keep it below 43deg? Why does it care since I set it to off in the profile? Why won’t it let me change the chamber temp while printing in order to stop the errors?

Print turned out beautiful regardless, even though I had to tap resume 20 times lol.

Cheers.

2

A couple of months ago I’ve posted exactly the same issue. Me myself and I could not identify a possible solution for this.

I do not understand this ether. Thats such a waste of energy and makes no sense at all.

I wished Bambulab would have come with a solution or at least did reply to my post to offer a workaround.

3

Because you made the chamber temperature settings wrong and that confused the machine.

And ASA-CF still requires chamber temp

1 Like
4

I agree. You can get passable ASA prints without an actively heated chamber, but they’re usually fragile and demand ridiculously slow print speeds.

When I printed ASA on my X1 Carbon, I used the bed heater to pre-warm the chamber as much as possible before starting the job.

And for anyone tempted to claim this is AI-generated: I’ve attached the image. Clear, precise writing can come from humans, too. :wink:

image
image1672×612 43 KB

1 Like
5

I guess my question was more about why does the printer throw this error when the chamber heating is turned off in the slicer. I don’t get this error with the heater off when printing PLA. That was where I was confused. More importantly, when it threw the first error after an hour of printing, there seems to be no way to turn it on manually during the print. So even if I made the mistake of not turning it on, I then had to leave the lid off for the entire print in order to prevent it from stopping every 20 mins or so due to the error.

6

Once it’s set you can’t change it mid print.

7

How about you provide some actionable advice to OP, instead of castigating them for not bowing to Bambu’s obfuscated rules?

Setting chamber temperature to 0 is supposed to turn off chamber heating and cooling. The Bambu Wiki says: “Setting the chamber temperature to 0 °C represents disabling the chamber temperature heating control.”

Fiberon ASA-CF (what OP is using) prints fine without chamber heating, the TDS recommends room temperature for printing. No heating or cooling needed, fine to set "chamber_temperatures”: [0] like Polymaker does

But then Bambu unwinds this with their default Machine start G-code for the H2S. If chamber_temperature is not set in the filament profile {if (overall_chamber_temperature >= 40)} ... {else} and the filament is not made by Bambu {if (!is_all_bbl_filament)}, it forces PETG cooling profiles M142 P1 R35 S40 T45 U0.3 V0.5 W0.8 O45 L1 ; third-party PETG including what is probably a 45C shutoff temp (conjecture about what O45 means). This is not Marlin - Marlin has no M142. And Bambu does not document M142. So we can only guess what this is doing, but the assumption is M142 is used for cooling profiles (it does not appear in GCode if the chamber can be hot), and this is forcing an overtemp pause at 45C, when non-Bambu filaments are used, in opposition to their own documentation about chamber temperature and M141

OP, posting the fix here and in a direct reply:

On the ‘Prepare’ page, hit the edit icon in the printer selection widget. In the pop-up window navigate to machine g-code tab, and Machine start g-code section. Find the lines
{if (!is_all_bbl_filament)}
M142 P1 R35 S40 T45 U0.3 V0.5 W0.8 O45 L1 ; set third-party PETG chamber autocooling
and replace with

{if (!is_all_bbl_filament)}
M142 P1 R35 S45 T60 U0.3 V0.5 W0.8 O60 L1 ; set third-party PETG chamber autocooling

This will allow much higher chamber temperatures before shutdown

8

This seems to be caused by Bambu’s custom M142 chamber cooling G-code, which now includes a possible shutdown temperature parameter. The fix is to change the H2S default machine start G-code to override their bad values. On the ‘Prepare’ page, hit the edit icon in the printer selection widget. In the pop-up window navigate to machine g-code tab, and Machine start g-code section. Find the lines
{if (!is_all_bbl_filament)}
M142 P1 R35 S40 T45 U0.3 V0.5 W0.8 O45 L1 ; set third-party PETG chamber autocooling
and replace with

{if (!is_all_bbl_filament)}
M142 P1 R35 S45 T60 U0.3 V0.5 W0.8 O60 L1 ; set third-party PETG chamber autocooling

This will allow much higher chamber temperatures before shutdown

9

Your statement “no cooling needed” is incorrect!

The TDS states room temperature, and +43C is not room temperature, so cooling is required.

So there is nothing wrong in the functioning of the printer IMHO.

That Bambulabs treat their own filaments differently, is because they know their filaments. They don’t know all the other ones.

If you start printing with a chamber temperature of 25C and keep on printing above 45C, there might still be nothing wrong, but the physical properties of the part will change. So simply ignoring the warning wouldn’t be good either.

Still, I can imagine that the OP doesn’t like the constant messages and required confirmations, and Bambulabs could consider a “do not warn anymore until print is finished” toggle.

With your mods I can probably print PLA in a chamber of 50C. Not sure if I would want that.

10

Hi Gerrit,

It looks like you may be a contributor to the printer profile machine start G-code for the H2S (and other printers). So hopefully you can weight in with authority here.

from my reading of the chamber cooling logic in the machine start G-code, it seems the M142 logic block is a vitrification temperature check to prevent high chamber temperatures causing filament softening and clogs at the print head.

I imagine this is downstream of src/libslic3r/printconfig.cpp setting a default vitrification temperature of 100C, before the slicer code then retrieves vitrification temperature from the filament profile. If missing, 100C is sticky and that’s dangerous with many low temp filaments.

The tech-debt of a magic number committed four years ago has come due, and now that the firmware for the H2 line has expanded functionality of the M142 command, including overtemp shutdown, we are forced to modify the machine start G-code to bypass the vitrification check.

If Bambu could share details about the custom M142 command, then we can work on a fix at the filament level (with filament start G-code) to overwrite M142 with values safe to the filament in use.

But because machine start G-code seems to run before filament start G-code, or filament start G-code is blocked from overwriting M142, I cannot run successive prints on a hot day, because the chamber starts above 45C and immediately triggers a cooling overtemp pause.

Bambu does not sell certain engineering filaments, and has been out-of-stock on ASA-CF for 6 months now. We must turn to 3rd party filaments to manufacture demanding parts, and well understand how chamber conditions affect the outcome. I can tell you that pausing and restarting dozens of times on a 12 hour print has far worse outcomes on physical properties than chamber temperature drifting over time, I have the parts to prove it before I found this workaround.

So until Bambu gives guidance on M142 override through filament profiles, or changes the magic number in the slicer allowing downstream fix for the M142 logic block, my only recourse is to modify the machine start G-code to force higher safe temperatures.

P.S.
This vitrification temperature logic obviates Bambu’s documented guidance for chamber temperature parameter from the Bambu Wiki:

(2) ASA, ABS:

Chamber temperature setting: The default chamber temperature setting is off (0 °C).

11

Sorry, but I don’t have anymore authority on gcode than anyone else. I would love to see a fully documented gcode command list, but unfortunately that doesn’t seem to be available.

But to come back to the issue, if you know that with the current ambient temperature and a build plate of 100C, the chamber temperature is going to be above 45C, my advice would be to set the chamber temp to 46C (or possibly better 60-65C) This will put the printer in heating mode, and wil not trigger any issues.

End result is a print job without any warnings, and still a good (probably even better layer adhesion).

It might require some tuning on the cooling, because higher chamber temperatures require more cooling. But you would have constant quality.

Imho the TDS is set to no heating, so you can print this basically on every printer and warping is negligible with CF filled filaments.

Another simple alternative could be to just open the door to get the chamber temperature down. You want good ventilation then due to the unhealthy vapors.

You could start trying to fix it in the gcode, but with a heatbed at 100C it’s very hard to keep the chamber below 45C anyway.

So in my opinion, enough simple solutions that don’t need gcode changes.